Metallurgist最新文献

A change in the amount of the viscous component was established when testing with a falling load during the aging process of metal that has and has not undergone antiflaking heat treatment. The influence of heat treatment, heating temperature, post-tempering cooling rate, normalization, and annealing on the cold resistance of pipe steel of strength category K60 was studied. The aging of metal that has not undergone antiflaking heat treatment for 33 weeks, as well as an increase in the post-annealing cooling rate, increases cold resistance. The influence of eutectoid transformation on the mobilization processes of atomic hydrogen at the ferrite/cementite interface was characterized. The scientific notation of the theory of hydrogen brittleness has been expanded.

Analysis of the current state of production of various types of fused zirconia (monoclinic and stabilized) was conducted. A practical possibility of obtaining stabilized zirconia from baddeleyite concentrate in experimental electric-arc furnace (EDP-600) was established. The obtained process and electrical parameters of smelting are recommended for use when producing fused zirconia from synthetic zirconia and baddeleyite concentrate using commercial electric-arc furnaces (DSP‑1.5, OKB-2126, etc). During carbothermic reduction of zircon concentrate in an electric-arc furnace (EDP-450), silica content in the fused product was decreased by 3 times to 10.9% SiO₂. To implement the final stage of the carbothermic technology for obtaining fused zirconia containing at least 95% ZrO₂, it is recommended to develop a pilot electric-arc system based on DS-05 electric-arc furnace.

This article reviews recent literature related to electronic waste (E-waste) processing. The extraction of precious metals is shown as the main economic driver of E‑waste processing. The study methodology is based on collecting and analyzing statistical data and performing comparative analytical methods. The theoretical aspect is based on a critical analysis of the research of Russian and international authors.

This article highlights the current pyro-, hydro-, and biometallurgical processing methods used for extraction of precious metals from E‑waste. A comparative analysis of known technologies for E‑waste processing is performed; their advantages and disadvantages are shown to achieve a cleaner waste disposal process.

The technological and environmental aspects of E‑waste processing, as well as the effect of toxic substances and harmful components in E‑waste processing, have been subjected to a detailed analysis. According to the analysis results, existing technologies must be revised for a comprehensive solution to environmental problems.

The increasing E‑waste formation demonstrates the necessity of new approaches and the development of innovative technologies for E‑waste processing. The use of E‑waste as an additional source of raw materials to produce precious and other valuable metals seems very promising.

It is shown that in FeAl/Fe₃Al/Fe(Al) coatings, formed on a steel substrate using explosion welding and subsequent heat treatment, the main failure mechanism is cohesive failure. Peeling and spalling of coatings occur only at high loads. It has been established that the hardness of a layered FeAl/Fe₃Al/Fe(Al) coating with a thickness of 440 μm increases from the substrate to the surface, reaches a maximum at a distance of 200 μm from the surface, and then decreases due to an increase in porosity. Relative wear resistance of the coating is about 1.5 times higher than that of the steel St3 substrate.

Improving the gas-dynamic and thermal modes of external heating of a sintering charge layer, including preheating the layer, igniting the charge, and subsequent heat treatment of the layer, is important for increasing the productivity of sintering machines, improving the sinter quality, and saving fuel. AF‑5 design solutions can fully achieve all these operations. When setting up the operation of the sintering machines, layer preheating is eliminated and the ignition hearth is moved onto the vacuum chamber no. 1. The hot air supply to the hearth, which prevents thermal shock when the layer emerges from under the hearth, is also eliminated.

In this study, because of charge heating with lime, deep throttling of the first vacuum chambers of the sintering machine, and the operation of the sintering machines at a charge layer height of 560 mm, the layer shrinkage was minimal. This finding confirmed the efficiency of the decision to eliminate charge layer preheating. The influence of the charge layer height on the operating mode of the ignition hearth is discussed. The ineffectiveness of sintering machine equipment used worldwide with two parallel prefabricated collectors, instead of one, and a sectional design is experimentally established. Technical solutions to eliminate the negative consequences of dismantling the waste gas recirculation system are clarified. Moreover, recommendations for modernizing prefabricated collectors for stage 1 gas purification from dust are detailed. The advantages of using exhaust guide vanes instead of throttling vacuum chambers after the ignition hearth have been experimentally demonstrated. The features of the operation of sintering machine exhausts in a single scheme with a desulfurization unit are considered.

Aluminum alloy wire rod is the basic material for manufacturing wires for overhead power lines constructed in the areas with different atmospheric conditions. There is a potential associated with the use of wire rods made of aluminum-zirconium alloys, which can improve the performance characteristics of the final products. This study is devoted to a method for determining rheological coefficients of the equation linking the strength properties (σ_s) of alloy Al–0.15Zr with deformation parameters ((overline{upvarepsilon }) and ξ) at process temperatures ranging from 300 to 500 °C. The coefficients were calculated based on the experimental data obtained during indirect determination of the deformation resistance by measuring the force of direct hot extrusion. The variable parameters of the experiment included: elongation ratio (λ), deformation temperature (T), and extrusion velocity (υ_ex). For each equation coefficient, characteristic curves demonstrating their dependence on the process temperature were plotted and used to find an approximating function.

This paper presents the generalized experience in developing and implementing technology for high specific natural gas consumption in blast furnaces at the Severstal Company. In-depth analysis was performed, problem areas in the technology of replacing coke with natural gas were identified and described, and corrective measures were developed at four process control levels. Only a systematic application of all elements of the developed technology enables us to achieve high economic indicators. Experience in technology development has made possible a specific natural gas consumption of more than 190 m³/t of cast iron and a solid fuel consumption of less than 350 kg/t of cast iron. The most efficient technology development was achieved at blast furnace No. 3, with natural gas consumption of over 210 m³/t of cast iron and solid fuel consumption of less than 325 kg/t of cast iron.

The paper describes the results of implementing modified designs of the working tools of a plug rolling mill. The plug design is modified to improve the rolling of the pipe wall thickness. The design of the bottom guide tool (the inlet trough of the mill) is improved to eliminate metal ruptures at the rear ends of thin-walled pipes, as well as to reduce downtime and rejection as unfinished products. The economic indicators of the proposed designs implemented in the longitudinal rolling process are presented.

In order to predict the shelf life of non-ferrous metals, laboratory studies into the kinetics of corrosion processes of metals under various temperature and humidity conditions were performed. The results of 12-month corrosion tests of the following non-ferrous metals are presented: aluminum, cobalt, copper, nickel, tin, lead, and zinc at various relative humidity and air temperature conditions. All the metals studied were found to be corrosion-resistant under atmospheric conditions at a relative humidity of no more than 80% and an air temperature of no more than 30 °C. An increase in air humidity from 70 to 95% and air temperature from 20 to 50 °C leads to an increase in corrosion-induced losses of metals, primarily for zinc, cobalt, and lead. During the tests, changes in the appearance of the sample surface were recorded. The chemical and phase composition of oxide films on the metal surface, as well as their morphology, were studied after different test periods. The results will be used in future works in developing methods for predicting the shelf life of non-ferrous metals.

A test stand is proposed that implements a test method with periodic wetting of samples to simulate the conditions of the inner surface of a gas pipeline. This test stand is a new scientific and technical solution for conducting corrosion tests under carbon dioxide corrosion conditions, including an assessment of the steel resistance to local corrosion. Tests involving this stand have shown that the device quickly enables an estimation of the rates of general and local corrosion of steel pipes. Several test cells (up to 14) in the corrosion stand and the possibility of varying their corrosion conditions enable the rapid study of the primary hazardous corrosion factors (mineral composition of the aqueous phase, partial pressure, and temperature). Moreover, this corrosion test method is sensitive to low CO₂ levels.